In the case of rail vehicles in which the wheel sets are guided rigidly in longitudinal direction or parallel with little longitudinal play in the running gear frame, the parallel attitude results in the formation of increased transverse forces and increased wear mainly at the end wheel sets because the outer rail is struck at an acute striking angle.
In the case of two or multi-axle running gears it is already known to steer the end wheel sets into an approximately radial attitude by displacement transversely to the direction of travel by means of longitudinal pull rods arranged at an angle to the longitudinal direction of the vehicle, wherein the outward turning of the longitudinal pull rods arranged at an angle creates a longitudinal displacement of the wheel set bearings which is opposed left and right in each case.
To relieve the rail of additional forces which result from the secondary bending of the running gear between the inside and outside rails, a known running gear is provided with a middle wheel set that can be displaced transversely.
The use of rod assemblies to couple the transverse displacements of the middle wheel sets with the wheel attitude of the end wheel sets is already known from different arrangements, but in most cases these are influenced by longitudinal forces through tractive or braking forces of the rail vehicle such that the control effect is negatively influenced.
The object of the invention is to create a three-axle running gear for rail vehicles which permits a limiting of the transverse forces acting on the displaced end wheel set and which also represents a structurally simple and robust solution.
This is achieved according to the invention in that the bogey frame, seen in longitudinal direction, has several sections, wherein at least the frontmost section, seen in the direction of travel of the rail vehicle, in which the leading wheel set is arranged, is connected horizontally pivotable to a second, rigid section. Because the transverse displacement of the end wheel set no longer takes place, as in the state of the art, with separate pull rods, but according to the invention directly by means of a pivotable section of the bogey frame, an extremely robust design is achieved which allows a limiting of the transverse force even at axle loads up to 250 kN and at travel speeds up to 230 km/h.
According to a preferred embodiment example of the invention the bogey frame has three sections, in each of which a wheel set is housed, wherein the front section with the leading wheel set and/or the rear section with the trailing wheel set is or are connected horizontally pivotably to the middle rigid section.
In order to be able to keep the ratio between the forces acting substantially transversely to the longitudinal direction of the running gear and those acting vertically on a wheel set to permissible values, preferably smaller than 1:3, a further embodiment example of the invention provides that the steering device is formed and arranged for the transverse displacement of at least one end wheel set by more than 30 mm, preferably more than 50 mm, wherein transverse displacements of 90 mm and more are also possible and desired.
According to a further preferred embodiment example of the invention the steering device has two wheel set guides which are formed by pivotable parts of the bogey frame, wherein the substantially parallel wheel set guides which are arranged opposing in relation to the middle longitudinal axis of the bogey frame are hinged at their one end to the rigid part of the bogey frame and coupled to each other via a guide rod preferably attached to the opposite end. In other words, the parts of the bogey frame that are arranged in longitudinal direction of the running gear in the front and/or rear section of the bogey frame are pivotably housed at the middle rigid section of the bogey frame and in this way form two wheel set guides arranged parallel on both sides of the middle longitudinal axis of the running gear, wherein the parallelism of the two wheel set guides is ensured via a guide rod coupling the two wheel set guides to each other. That is to say, the pivotable section of the bogey frame is displaced as a parallelogram transversely to the longitudinal axis of the bogey frame.
In order to give the bogey frame according to the invention the necessary stability despite the pivotability of a section of the bogey frame, it is provided according to a further embodiment of the invention that the wheel set guides are formed substantially L-shaped seen from the side and are connected spatially movable with their vertical legs via at least one, preferably two joint(s), preferably rocker bearings, to the rigid part of the bogey frame, whereby not only is the pivotable section of the bogey frame horizontally movable but also vertical relative movements between the pivotable and the rigid section of the bogey frame can be compensated.
In order to be able to keep small the wear occurring at the wheel sets as a result of the transverse displacement of the wheel set, it has proved advantageous if the lateral excursion of the wheel set guides, i.e. the transverse displacement of the pivotable section of the bogey frame, is limited, this being achieved according to a further embodiment example if the steering device has an adjusting device for aligning the horizontally pivotable section of the bogey frame in longitudinal direction of the rigid bogey frame section.
A structurally simple solution results if the adjusting device has at least two, preferably hydraulic, adjusting cylinders operating diametrically opposed, which are each allocated to a wheel set guide and housed movable in rotation to a wheel set guide with one end and connected at the opposite end to the rigid bogey frame section, preferably to a holding element, projecting into the pivotable front section of the bogey frame, of the rigid bogey frame section.
If the adjusting cylinders operatively connected via a supply line each have an inner cylinder arranged movable in the adjusting cylinder casing and also a piston housed movable in the inner cylinder, the adjusting cylinders not only serve as a limiting device for lateral excursion of the pivotable section of the bogey frame, but also make possible the alignment of the pair of wheel set guides with the exact longitudinal direction of the bogey frame, especially if the two pistons of the two adjusting cylinders can be or are acted on by a system pressure that can preferably be changed.
To this end, according to a further embodiment example of the invention the supply lines are connected to a memory, preferably a bubble memory, for the pressure medium, wherein the system pressure is kept largely constant via the bubble memory and the supply lines.
As the lateral excursion of the movable frame parts can be set via the system pressure prevailing at the adjusting cylinders, it is possible, via the system pressure, to limit the transverse forces acting on the wheel set and keep them in a range in which firstly the wear occurring is as small as possible and secondly rolling motions which can occur when there are freely mobile frame parts of the bogey frame can be reduced or completely avoided.
In order to minimize the wear at the mechanical stops, a further embodiment example of the invention provides that the inner cylinder and/or the piston of at least one adjusting cylinder is/are damped in one or both end-positions by a damping device, wherein it has proved advantageous for an effective damping of the vertical, lateral and longitudinal movements of the wheel set or of the wheel set bearing if the preferably hydraulic damping element can be set according to the travel speed of the rail vehicle and/or the excursion of the pivotable section of the bogey frame and/or the direction of movement of the inner cylinder(s).
To transmit the tractive and braking forces of the wheel sets to the bogey frame, a further embodiment example of the invention provides that at least one wheel set of the running gear is coupled to the rigid section of the bogey frame via preferably two pull-push rods, wherein the pull-push rods are movably connected at their one end to the axle box case preferably formed as carrier for the primary springs and at their other end to the rigid section of the bogey frame.
If the distance between the reversing points of the pull-push rods is greater, at least at a wheel set arranged in a pivotable section of the bogey frame, than the distance between the reversing points of the pull-push rods at the rigid section of the bogey frame, the result, as a consequence of the angled arrangement of the pull-push rods, is a steering angle by which the wheel set axle that is normal to the longitudinal axis of the rigid section of the bogey frame when travelling straight ahead can be pivoted. The steering angle depends on the spread angle which the two pull-push rods arranged at an angle enclose with each other.
In order to compensate the inequality during the lateral excursion between the wheel set, loose in itself, and the pivotable frame parts of the bogey frame that are guided by means of the adjusting cylinders, and thus prevent the primary springs arranged between the wheel set and the pivotable parts of the bogey frame from being too greatly warped or twisted, a further embodiment example of the invention provides that, between the primary springs of the wheel set and the pivotable parts of the bogey frame, preferably plate-shaped sliding elements are arranged against which the primary springs rest with their end lying opposite the carrier, wherein a structurally particularly simple solution is obtained if the sliding elements are attached movably, preferably centered via a pin, to the pivotable parts of the bogey frame.
To relieve the running gear of the braking forces transmitted by means of the pull-push rods from the wheel sets to the running gear, it is provided according to a further embodiment example of the invention that the running gear is connected to the vehicle body of the rail vehicle via a device for the transmission of the braking and tractive forces, wherein the device has a first linking element hinged to the vehicle body and a second linking element hinged to the running gear, in particular to the rigid section of the bogey frame, and a connection element connecting the two linking elements, wherein as small as possible a wheel set relief is achieved if the device for the transmission of the braking and tractive forces is arranged lying deeper relative to the wheel set axles.